1. Field of the Invention
The present disclosure relates generally to shutter assemblies and, more particularly, to shutters relying on electromagnetic, spring, and/or biasing forces to open and/or close a plurality of shutter blades.
2. Description of Related Art
Electromagnetic shutter assemblies are commonly used in photographic and other applications requiring a relative rapid shutter exposure pulse. Such shutter assemblies typically employ a number of shutter blades that are movable to expose a central aperture of the assembly. For example, such shutter blades can be movable between an open position exposing the central aperture of the shutter, and a closed position blocking the central aperture. In the open position, light may be allowed to pass through the central aperture to reach a lens and/or film utilized with a corresponding photographic device such as a camera. Once a desired exposure time has elapsed, the shutter blades may then be moved to the closed position, thereby blocking light from passing through the central aperture.
Such shutter blades are typically coupled to one or more drive components configured to rapidly and controllably transition the blades between the open and closed positions. Such components may include, for example, a drive ring and an actuator coupled to the drive ring. In such an arrangement, the drive ring may be rotatably mounted within, for example, a base plate of the shutter assembly, and the shutter blades may be coupled to both the drive ring and the base plate. For example, rotation of the drive ring may cause each of the shutter blades to pivot about a respective pin formed in the base plate. In such a shutter assembly, the drive ring may also include a number of pins slidably disposed within respective slots formed in the shutter blades. Thus, rotating the drive ring may cause the pins of the drive ring to slide in the respective slots of the shutter blades, thereby causing desired movement of the shutter blades. Generally, a linear electric motor is used to rotate the drive ring. When activated, the motor may move, for example, a lever arm, gear, and/or other combination of linkages, thereby causing the drive ring to rotate the shutter blades to an open position. In exemplary shutters, such a motor can then be deactivated, and a spring or other biasing member may cause counter-rotation of the drive ring in order to close the shutter blades.
Known shutters, however, typically suffer from several undesirable deficiencies. For example, the operating characteristics of certain cameras and/or the exposure requirements for different photographic applications may require that the size of a shutter aperture formed by the plurality of shutter blades be adjustable. Known shutters, however, may not allow for such adjustability.
Moreover, to reduce wear on the different shutter components, it may be desirable to damp the movement of such components during operation of the shutter. However, known shutters may not be configured to adjust the position of such dampers in response to changes in shutter aperture size. In addition, most known shutters may utilize a large number of complicated linkages and/or control strategies to adjust the desired size of the shutter aperture.
Since such complicated structures and/or methods of control may increase the size, cost, and complexity of known shutters, and may also result in reduced reliability, it may be desirable to reduce and/or eliminate such complexities in favor of a more streamlined shutter design. In particular, it may be desirable to reduce the number of mechanical components utilized to set and/or change the size of the shutter aperture formed by the shutter blades. Such a reduction in components and/or such a simplification in control strategy may reduce the overall cost of the shutter and may improve operational characteristics such as reliability and component wear.
Moreover, known shutters may not be capable of determining the exact position of one or more of the shutter blades during travel between the open and closed positions. For example, known shutters typically sense the position of one or more shutter blades at either the beginning or the end of travel. With only limited information regarding the position of the shutter blades during travel, it may difficult for known shutters to accurately control shutter blade movement or to facilitate highly precise modifications in, for example, opening speed, closing speed, and/or shutter aperture size.
In addition, while some shutters may utilize a set of iris blades to form an adjustable iris opening of the shutter, and a set of shutter blades configured to open and close behind the iris blades, the exposure time of such shutters is limited by the travel of the shutter blades behind the iris blades. For example, while the iris blades may be set for a relatively small iris aperture size, the shutter blades in such shutters may still be required to rotate between the fully open position (forming a shutter aperture much larger than the iris aperture) and the fully closed position (blocking light from passing through the relatively small iris aperture). Thus, since the shutter blades in such shutters travel well beyond the iris opening, such shutters may not be appropriate in applications requiring relatively short dwell times.
The exemplary embodiments of the present disclosure are aimed at addressing one or more of the deficiencies discussed above.